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Abstract Maize (Zea mays L.) productivity in Kenya has witnessed a decline attributed to the effects of climate change and biophysical constraints. The assessment of agronomic practices across agroecological zones (AEZs) is limited by inadequate data quality, hindering a precise evaluation of maize yield on a large scale. In this study, we employed the DSSAT‐CERES‐Maize crop model (where CERES is Crop Environment Resource Synthesis and DSSAT is Decision Support System for Agrotechnology Transfer) to investigate the impacts of different agronomic practices on maize yield across different AEZs in two counties of Kenya. The model was calibrated and evaluated with observed grain yield, biomass, leaf area index, phenology, and soil water content from 2‐year experiments. Remote sensing (RS) images derived from the Sentinel‐2 satellite were integrated to delineate maize areas, and the resulting information was merged with DSSAT‐CERES‐Maize yield simulations. This facilitated a comprehensive quantification of various agronomic measures at pixel scales. Evaluation of agronomic measures revealed that sowing dates and cultivar types significantly influenced maize yield across the AEZs. Notably, AEZ II and AEZ III exhibited elevated yields when implementing combined practices of early sowing and cultivar H614. The impacts of optimal management practices varied across the AEZs, resulting in yield increases of 81, 115, and 202 kg ha−1 in AEZ I, AEZ II, and AEZ III, respectively. This study underscores the potential of the CERES‐Maize model and high‐resolution RS data in estimating production at larger scales. Furthermore, this integrated approach holds promise for supporting agricultural decision‐making and designing optimal strategies to enhance productivity while accounting for site‐specific conditions.

Finding consensus in definitions of commonly-used terms and concepts is a key requirement to enable cooperations between interdisciplinary scientists and practitioners in inter- or transdisciplinary projects. In research on sustainable agriculture, the term ‘landscape’ is emphasised in particular, being used in studies that range from biogeochemical to socio-economic topics. However, it is normally used in a rather unspecific manner. Moreover, different disciplines assign deviating meanings to this term, which impedes interdisciplinary understanding and synthesis. To close this gap, a systematic literature review from relevant disciplines was conducted to identify a common understanding of the term “landscape”. Three general categories of landscape conceptualizations were identified. In a small subset of studies, “landscape” is defined by area size or by natural or anthropogenic borders. The majority of reviewed papers, though, define landscapes as sets of relationships between various elements. Selection of respective elements differed widely depending on research objects. Based on these findings, a new definition of landscape is proposed, which can be operationalized by interdisciplinary researchers to define a common study object and which allows for sufficient flexibility depending on specific research questions. It also avoids over-emphasis on specific spatio-temporal relations at the “landscape scale”, which may be context-dependent. Agricultural landscape research demands for study-specific definitions which should be meticulously provided in the future.

Transformation of agriculture to realise sustainable site-specific management requires comprehensive scientific support based on field experiments to capture the complex agroecological process, incite new policies and integrate them into farmers’ decisions. However, current experimental approaches are limited in addressing the wide spectrum of sustainable agroecosystem and landscape characteristics and in supplying stakeholders with suitable solutions and measures. This review identifies major constraints in current field experimentation, such as a lack of consideration of multiple processes and scales and a limited ability to address interactions between them. It emphasizes the urgent need to establish a new category of landscape experimentation that empowers agricultural research on sustainable agricultural systems, aiming at elucidating interactions among various landscape structures and functions, encompassing both natural and anthropogenic features. It extensively discusses the key characteristics of landscape experiments and major opportunities to include them in the agricultural research agenda. In particular, simultaneously considering multiple factors, and thus processes at different scales and possible synergies or antagonisms among them would boost our understanding of heterogeneous agricultural landscapes. We also highlight that though various studies identified promising approaches with respect to experimental design and data analysis, further developments are still required to build a fully functional and integrated framework for landscape experimentation in agricultural settings.

Despite human activities are key influencing factors for cropland soil organic matter (SOM), detailed characterization of human activities has always been limited in the digital mapping of SOM due to the lack of proper representations of human’s cropland use activities. Crop rotation is an essential human agricultural practice significantly affecting the spatial–temporal variations of SOM due to the periodically dynamic changes of crops. Thus, incorporating crop rotation in the digital soil mapping holds high potential for improving SOM prediction. Here, we applied time-series radar Sentinel-1 and optical Sentinel-2 to map crop rotation systems by a hierarchical rule-based method. Then we explored the effectiveness of incorporating such information in predicting SOM by implementing various combinations of predictive variables. We chose a typical multiple cropping region with various crop rotations in southern China. The model performance was evaluated by 10-fold cross-validation. Results showed significant differences in SOM among the crop rotation systems, and the single rice rotated with vegetables has the highest SOM followed by the high-diversity vegetables and long-term orchard systems. Adding crop rotation enhanced the predictability of SOM with a decrease in RMSE by 7% and an increase in R2 by 24%. Furthermore, the crop rotation systems appeared more important in the predictive models than the soil, topographic, and climatic variables. Our results demonstrated the effectiveness of including crop rotation in predicting SOM over complex agricultural landscapes. Our study indicated that human activities should be characterized more detailedly in cropland soil mapping, and that crop rotation containing information on the seasonal dynamics of cropland may be an option for such characterization.

Multifunctional and diversified agriculture can address diverging pressures and demands by simultaneously enhancing productivity, biodiversity, and the provision of ecosystem services. The use of digital technologies can support this by designing and managing resource-efficient and context-specific agricultural systems. We present the Digital Agricultural Knowledge and Information System (DAKIS) to demonstrate an approach that employs digital technologies to enable decision-making towards diversified and sustainable agriculture. To develop the DAKIS, we specified, together with stakeholders, requirements for a knowledge-based decision-support tool and reviewed the literature to identify limitations in the current generation of tools. The results of the review point towards recurring challenges regarding the consideration of ecosystem services and biodiversity, the capacity to foster communication and cooperation between farmers and other actors, and the ability to link multiple spatiotemporal scales and sustainability levels. To overcome these challenges, the DAKIS provides a digital platform to support farmers' decision-making on land use and management via an integrative spatiotemporally explicit approach that analyses a wide range of data from various sources. The approach integrates remote and in situ sensors, artificial intelligence, modelling, stakeholder-stated demand for biodiversity and ecosystem services, and participatory sustainability impact assessment to address the diverse drivers affecting agricultural land use and management design, including natural and agronomic factors, economic and policy considerations, and socio-cultural preferences and settings. Ultimately, the DAKIS embeds the consideration of ecosystem services, biodiversity, and sustainability into farmers' decision-making and enables learning and progress towards site-adapted small-scale multifunctional and diversified agriculture while simultaneously supporting farmers' objectives and societal demands.

Abstract Successful conservation efforts have led to recent increases of large mammals such as European bison Bison bonasus, moose Alces alces and grey wolf Canis lupus and their return to former habitats in central Europe. While embraced by some, the recovery of these species is a controversial topic and holds potential for human‐wildlife conflicts. Involving the public has been suggested to be an effective method for monitoring wildlife and mitigating associated conflicts. To assess two interrelated prerequisites for engaging people in Citizen Science (CS)—knowledge of returning species and respondents' readiness to participate in CS activities for monitoring and managing these species—we conducted a survey (questionnaire) in two wildlife parks located in different states of Germany. Based on 472 complete questionnaires, we developed generalized linear models to understand how sociodemographic variables and exposure to the species affected visitors' knowledge of each species, and to investigate if sociodemographic variables and knowledge influenced the likelihood of visitors to participate in CS activities. Almost all visitors were aware of the returning wolf population, while knowledge and awareness about bison and moose were significantly lower. Knowledge of the two herbivores differed geographically (higher knowledge of moose in the north‐eastern state), possibly indicating a positive association between exposure to the species and knowledge. However, models generally performed poorly in predicting knowledge about wildlife, suggesting that such specific knowledge is insufficiently explained by sociodemographic variables. Our model, which explained stated willingness in CS indicated that younger participants and those with higher knowledge scores in the survey were more willing to engage in CS activities. Overall, our analyses highlight how exposure to large mammals, knowledge about wildlife and human demographics are interrelated—insights that are helpful for effectively recruiting citizen scientists for wildlife conservation. Read the free Plain Language Summary for this article on the Journal blog.

Crop rotation increases crop yield, improves soil health, and reduces plant disease. Mapping crop rotation is difficult because crop data from a single time point do not sufficiently represent the dynamics of a system. Studies have tried to map crop rotation by sequentially combining crop maps. However, this produced a large number of meaningless crop sequences, hindering the assessment of rotational benefits at regional scales. Here, we propose a crop rotation classification scheme that integrates temporal information into static crop maps and develop an innovative approach to map crop rotation. We chose a typical multiple cropping region in southern China. Given that the landscape is characterized by high crop diversity (e.g., food crops, cash crops, and permanent crops) and variable cropping intensity, our classification scheme first defines three main rotation systems, i.e., paddy, vegetable, and orchard systems, and then further divides the systems into nine subsystems according to their seasonal dynamics. Finally, we apply time series of Sentinel-1 and Sentinel-2 images to identify the systems by a hierarchical rule-based method. The map of crop rotation systems in 2020 had producer, user, and overall accuracies of 81%, 79%, and 81%, respectively. The results indicate that integrating temporal information into the classification scheme is vital to representing complex rotation systems and that remotely sensed temporal dynamics of crops are useful to characterize these systems. It also shows that crop rotation can be mapped directly rather than aggregating multiple crop layers, thus providing a new perspective for mapping and understanding crop rotation systems.

Endophytes colonizing plant tissue play an essential role in plant growth, development, stress tolerance and plant protection from soil-borne diseases. In this study, we report the diversity of cultivable endophytic bacteria associated with marigold (Calendula officinalis L.) by using 16S rRNA gene analysis and their plant beneficial properties. A total of 42 bacterial isolates were obtained from plant tissues of marigold. They belonged to the genera Pantoea, Enterobacter, Pseudomonas, Achromobacter, Xanthomonas, Rathayibacter, Agrobacterium, Pseudoxanthomonas, and Beijerinckia. Among the bacterial strains, P. kilonensis FRT12, and P. rhizosphaerae FST5 showed moderate or vigorous inhibition against three tested plant pathogenic fungi, F. culmorum, F. solani and R. solani. They also demonstrated the capability to produce hydrolytic enzymes and indole-3-acetic acid (IAA). Five out of 16 isolates significantly stimulated shoot and root growth of marigold in a pot experiment. The present study reveals that more than half of the bacterial isolates associated with marigold (C. officinalis L.) provided antifungal activity against one or more plant pathogenic fungi. Our findings suggest that medicinal plants with antimicrobial activity could be a source for selecting microbes with antagonistic activity against fungal plant pathogens or with plant growth stimulating potential. These isolates might be considered as promising candidates for the improvement of plant health.

The current study aimed to determine the diversity of culturable endophytic bacteria associated with horseradish (Armoracia rusticana G.Gaertn., B.Mey.&Scherb.) grown in Chatkal Biosphere Reserve of Uzbekistan and their antimicrobial potentials. The bacteria were isolated from plant leaves and root tissues using culture-dependent techniques. The 16S rRNA sequences similarities of endophytic bacteria isolated from A. rusticana showed that isolates belong to species Paenibacillus, Raoultella, Stenotrophomonas, Pseudomonas, Serratia, Microbacterium, Enterobacter, Achromobacter, Brevibacterium, Pantoea, and Erwinia. The isolated endophytic bacteria Stenotrophomonas maltophilia KRT1, Serratia ficaria KRT5, and Pantoea agglomerans KLT4 possess antimicrobial activities against human pathogenic bacteria Staphylococcus aureus, Escherichia coli, and Candida albicans. The endophytic bacteria Paenibacillus typhae KRN1, Stenotrophomonas maltophilia KRT1, Pseudomonas kilonensis KRT11, Pseudomonas umsongensis KRT21, Brevibacterium frigoritolerans KLT2 and Pantoea agglomerans KLT4 inhibited phytopathogenic fungi Rhizoctonia solani, Fusarium culmorum, and F. solani. These findings indicate that plant endophytic bacteria with antimicrobial activity could be a source for producing agriculturally and pharmaceutically important antimicrobial compounds.

Bacillus pumilus strain TUAT1 is a plant growth-promoting bacterium (PGPB) applied as a biofertilizer, containing its spores, for rice. In this study, we analyzed the short-term effects of biofertilization on plant growth in the nursery and long-term effects on plant vegetative growth, yield, and lodging resistance in paddy fields using animal feed rice (‘Fukuhibiki’ and line LTAT-29 which was recently officially registered as a cultivar ‘Monster Nokodai 1′) and fodder rice (line TAT-26). The effects of the biofertilization were analyzed under two nitrogen treatments and at two transplanting distances in the field. The application of 107 colony forming units (CFU) mL−1 bacterial spore solution to seeds on plant box significantly improved the initial growth of rice. The biofertilizer treatment with this strain at 107 CFU g−1 onto seeds in nursery boxes increased the nitrogen uptake at the early growth of rice in the field, resulting in higher growth at the late vegetative growth stage (e.g., tiller number and plant height). Furthermore, the improvement of growth led to increases of not only yield components such as the total panicle number (TPN) and the number of spikelets in a panicle (NSP) in LTAT-29 but also the straw yield and quality of TAT-26. The lodging resistances of these forage rice plants were also improved due to the increased root development and photosynthesis creating tougher culms.

Numerous reports confirm a positive impact of biochar amendments on soil enzyme activities, nutrient cycles, and, finally, plant growth and development. However, reports explaining the process behind such diverse observations are scarce. The aim of the present study was (1) to evaluate the effect of biochar on the growth of purslane (Portulaca oleracea L.) and nutrients; (2) to determine the response of rhizosphere enzyme activities linked to soil phosphorus cycling after bio-char amendment under non–saline and saline soil conditions. Furthermore, we investigate whether adding biochar to soil alters the abundance of P-cycling-related bacteria. Two rates of biochar (2% and 4%) were applied in pot experiments. Biochar addition of 2% significantly increased plant growth under non-saline and saline soil conditions by 21% and 40%, respectively. Moreover, applying biochar increased soil microbial activity as observed by fluorescein diacetate (FDA) hydrolase activity, as well as phosphomonoesterase activities, and the numbers of colony-forming units (CFU) of P-mobilizing bacteria. Soil amended with 2% biochar concentration increased total soil nitrogen (Nt), phosphorus (P), and total carbon (Ct) concentrations by 18%, 15%, and 90% under non-saline soil conditions and by 29%, 16%, and 90% in saline soil compared the control, respectively. The soil FDA hydrolytic activity and phosphatase strongly correlate with soil Ct, Nt, and P contents. The rhizosphere soil collected after biochar amendment showed a higher abundance of tricalcium phosphate-solubilizing bacteria than the control soil without biochar. Overall, this study demonstrated that 2% maize-derived biochar positively affects halophyte plant growth and thus could be considered for potential use in the reclamation of degraded saline soil.

Desertified land covers one-fourth of the world’s total land area. Meeting the high food demands in areas affected by desertification is a major problem. This case study provided fundamental information to demonstrate the potential for utilizing the desertified land. The soybean trial was established in two sandy clay loam soils (desertified land) and one silty clay loam soil. Two types of biochar were applied as treatments. We aimed to investigate the response of soybean plants to soil structure, soil nutrient condition, and biochar amendment in the two types of soil. In addition, ridge regression was employed to model the plant growth indicators by soil structure, soil nutrients condition, soil water content, and biochar amendment. We conclude that (1) overall soil productivity in sandy clay loam soil is lower than in silty clay loam soil. The sandy clay loam soil may have high efficacy for crop production due to its higher harvest index. (2) Aggregate size 0.5–1 mm, 1–2 mm, and 2–3 mm indicated more important in plant biomass formation in silty clay loam soil. The low aggregate stability of sandy clay loam soil made the field more vulnerable to wind erosion in the semi-arid monsoon climate. (3) Cob biochar and wood biochar increased soybean shoot biomass by 48.7% and 45.0% in silty clay loam soil. (4) The higher N-fixing ability of nodules in sandy clay loam soil indicates an advantage to reduce the use of N-fertilizers in desertified areas. (5) Exponential polynomial regression ameliorated the accuracy of prediction of plant growth indicators in comparison to linear regression.

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development.

Soil salinity has emerged as a serious issue for global food security. It is estimated that currently about 62 million hectares or 20 percent of the world’s irrigated land is affected by salinity. The deposition of an excess amount of soluble salt in cultivable land directly affects crop yields. The uptake of high amount of salt inhibits diverse physiological and metabolic processes of plants even impacting their survival. The conventional methods of reclamation of saline soil which involve scraping, flushing, leaching or adding an amendment (e.g., gypsum, CaCl2, etc.) are of limited success and also adversely affect the agro-ecosystems. In this context, developing sustainable methods which increase the productivity of saline soil without harming the environment are necessary. Since long, breeding of salt-tolerant plants and development of salt-resistant crop varieties have also been tried, but these and aforesaid conventional approaches are not able to solve the problem. Salt tolerance and dependence are the characteristics of some microbes. Salt-tolerant microbes can survive in osmotic and ionic stress. Various genera of salt-tolerant plant growth promoting rhizobacteria (ST-PGPR) have been isolated from extreme alkaline, saline, and sodic soils. Many of them are also known to mitigate various biotic and abiotic stresses in plants. In the last few years, potential PGPR enhancing the productivity of plants facing salt-stress have been researched upon suggesting that ST-PGPR can be exploited for the reclamation of saline agro-ecosystems. In this review, ST-PGPR and their potential in enhancing the productivity of saline agro-ecosystems will be discussed. Apart from this, PGPR mediated mechanisms of salt tolerance in different crop plants and future research trends of using ST-PGPR for reclamation of saline soils will also be highlighted.

The diversity of salt-tolerant cultivable endophytic bacteria associated with the halophyte New Zealand spinach (Tetragonia tetragonioides (Pall.) Kuntze) was studied, and their plant beneficial properties were evaluated. The bacteria isolated from leaves and roots belonged to Agrobacterium, Stenotrophomonas, Bacillus, Brevibacterium, Pseudomonas, Streptomyces, Pseudarthrobacter, Raoultella, Curtobacterium, and Pantoea. Isolates exhibited plant growth-promoting traits, including the production of a phytohormone (indole 3-acetic-acid), cell wall degrading enzymes, and hydrogen cyanide production. Furthermore, antifungal activity against the plant pathogenic fungi Fusarium solani, F. oxysporum, and Verticillium dahliae was detected. Ten out of twenty bacterial isolates were able to synthesize ACC deaminase, which plays a vital role in decreasing ethylene levels in plants. Regardless of the origin of isolated bacteria, root or leaf tissue, they stimulated plant root and shoot growth under 200 mM NaCl conditions. Our study suggests that halophytes such as New Zealand spinach are a promising source for isolating halotolerant plant-beneficial bacteria, which can be considered as potentially efficient biofertilizers in the bioremediation of salt-affected soils.

Agricultural land use systems have been optimized for producing provisioning ecosystem services (ES) in the past few decades, often at the expense of regulating and cultural services. Research has focused mainly on the supply side of ES and related trade-offs, but the demand side for regulatory services remains largely neglected. The objective of this paper is to evaluate the usefulness of participatory geographic information system (PGIS) methods for demand assessment in larger rural and agrarian contexts by identifying spatially explicit demand patterns for ES, thereby enlarging the body of participatory approaches to ES-based land use management. Accordingly, we map, assess, and statistically and spatially analyze different demands for five ES by different stakeholder groups in agricultural landscapes in three case studies. The results are presented in a stakeholder workshop and prerequisites for collaborative ES management are discussed. Our results show that poor correlation exists between stakeholder groups and demands for ES; however, arable land constitutes the highest share of the mapped area of demands for the five ES. These results have been validated by both the survey and the stakeholder workshop. Our study concludes that PGIS represents a useful tool to link demand assessments and landscape management systematically, especially for decision support systems.

Licorice (Glycyrrhiza uralensis Fisch.) is a salt and drought tolerant legume suitable for rehabilitating abandoned saline lands, especially in dry arid regions. We hypothesized that soil amended with maize-derived biochar might alleviate salt stress in licorice by improving its growth, nutrient acquisition, and root system adaptation. Experiments were designed to determine the effect of different biochar concentrations on licorice growth parameters, acquisition of C (carbon), nitrogen (N), and phosphorus (P) and on soil enzyme activities under saline and non-saline soil conditions. Pyrolysis char from maize (600 °C) was used at concentrations of 2% (B2), 4% (B4), and 6% (B6) for pot experiments. After 40 days, biochar improved the shoot and root biomass of licorice by 80 and 41% under saline soil conditions. However, B4 and B6 did not have a significant effect on shoot growth. Furthermore, increased nodule numbers of licorice grown at B4 amendment were observed under both non-saline and saline conditions. The root architectural traits, such as root length, surface area, project area, root volume, and nodulation traits, also significantly increased by biochar application at both B2 and B4. The concentrations of N and K in plant tissue increased under B2 and B4 amendments compared to the plants grown without biochar application. Moreover, the soil under saline conditions amended with biochar showed a positive effect on the activities of soil fluorescein diacetate hydrolase, proteases, and acid phosphomonoesterases. Overall, this study demonstrated the beneficial effects of maize-derived biochar on growth and nutrient uptake of licorice under saline soil conditions by improving nodule formation and root architecture, as well as soil enzyme activity.

To analyse the 137Cs distribution and migration under various fractions of organic matter layers, this study investigated easily recognizable, originally shaped organic L-fractions, and not easily recognizable, early fermented and fragmented organic F-fractions, of both oak (Quercus serrata) and cedar (Cryptomeria japonica) sampled from Osawa watershed sites at Nihonmatsu City, Fukushima Prefecture, Japan. The organic materials were put on top of soil columns from Field Museum (FM) Tamakyuryo in Hachioji City, Tokyo. The 137Cs vertical distribution in forest soil profiles was analyzed using the relaxation mass depth, ho (kg m−2). Soil columns with both L and F- organic layer fractions of both oak and cedar, labelled as Oak-L, Oak-F, Cedar-L and Cedar-F with four replications (n = 16), were set up by the laboratory column-based method and kept under five months’ incubation period. Soil columns after incubation were sampled at depths of 0–1 cm, 1–2 cm, 2–5 cm and 5–10 cm. Results of 137Cs inventory in the organic fractions showed that 86% (oak and cedar) of the total organic layer fractions 137Cs inventory accumulated within the F-layer, indicating that the transformation of litter is a huge source for potentially mobile 137Cs, especially the oak F-layer (67% 137Cs inventory) and further continuous transfer into the forest soil mineral layers. A higher ho in L treated soils (Oak-L and Cedar-L) compared to the F treatments implied that the low 137Cs amounts penetrated faster and deeper due to their water-soluble nature. Furthermore, Cedar-F showed a higher ho of 24.3 kg m−2 than Oak-F of ho, 14.0 kg m−2, and a significant positive relationship between 137Cs retention and total carbon (TC) (p < 0.05) suggested the influence of soil organic matter on 137Cs penetration and retention. The C/N (carbon nitrogen ratio) results revealed that organic matter fractions of high C/N including 137Cs, as observed in Cedar-F, in which decomposition does not advance, penetrates soil depths while the organic matter fraction of low C/N, observed in Oak-F, showed that decomposition advanced to release 137Cs which was held by adsorption unto the RIP (radiocesium interception potential) of soil surface. In addition, infiltration by water as a transportation process was suggested to largely influence the downward migration and retention of 137Cs at lower depths of Cedar-F.

Chickpea (Cicer arietinum L.) is an important legume originating in the Mediterranean and the Middle East and is now cultivated in several varieties throughout the world due to its high protein and fiber content as well as its potential health benefits. However, production is drastically affected by prevalent water stress in most soybean-growing regions. This study investigates the potential of biochar to affect chickpea-Rhizobium symbiotic performance and soil biological activity in a pot experiment. Two different biochar types were produced from maize using different pyrolysis techniques, i.e., by heating at 600°C (MBC) and by batch-wise hydrothermal carbonization at 210°C (HTC), and used as soil amendments. The plant biomass, plant nutrient concentration, nodule numbers, leghemoglobin (Lb) content, soil enzyme activities, and nutrient contents of the grown chickpeas were examined. Our results indicated that plant root and shoot biomass, the acquisition of N, P, K, and Mg, soil nutrient contents, soil alkaline and acid phosphomonoesterases, and proteases were significantly increased by HTC char application in comparison to MBC char under both well-watered and drought conditions. Furthermore, the application of both biochar types caused an increase in nodule number by 52% in well-watered and drought conditions by improving the symbiotic performance of chickpea with Mesorhizobium ciceri. Rhizobial inoculation combined with HTC char showed a positive effect on soil FDA activity, proteases and alkaline phosphomonoesterases under well-watered and drought conditions compared to the control or MBC char-amended soils. This concept, whereby the type of producing biochar plays a central role in the effect of the biochar, conforms to the fact that there is a link between biochar chemical and physical properties and enhanced plant nutrient acquisition, symbiotic performance and stress tolerance.

To compare how different analytical methods explain crop yields from a long-term field experiment (LTFE), we analyzed the grain yield of winter wheat (WW) under different fertilizer applications in Müncheberg, Germany. An analysis of variance (ANOVA), linear mixed-effects model (LMM), and MP5 regression tree model were used to evaluate the grain yield response. All the methods identified fertilizer application and environmental factors as the main variables that explained 80% of the variance in grain yields. Mineral nitrogen fertilizer (NF) application was the major factor that influenced the grain yield in all methods. Farmyard manure slightly influenced the grain yield with no NF application in the ANOVA and M5P regression tree. While sources of environmental factors were unmeasured in the ANOVA test, they were quantified in detail in the LMM and M5P model. The LMM and M5P model identified the cumulative number of freezing days in December as the main climate-based determinant of the grain yield variation. Additionally, the temperature in October, the cumulative number of freezing days in February, the yield of the preceding crop, and the total nitrogen in the soil were determinants of the grain yield in both models. Apart from the common determinants that appeared in both models, the LMM additionally showed precipitation in June and the cumulative number of days in July with temperatures above 30 °C, while the M5P model showed soil organic carbon as an influencing factor of the grain yield. The ANOVA results provide only the main factors affecting the WW yield. The LMM had a better predictive performance compared to the M5P, with smaller root mean square and mean absolute errors. However, they were richer regressors than the ANOVA. The M5P model presented an intuitive visualization of important variables and their critical thresholds, and revealed other variables that were not captured by the LMM model. Hence, the use of different methods can strengthen the statement of the analysis, and thus, the co-use of the LMM and M5P model should be considered, especially in large databases involving multiple variables.

Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both greenhouse and field conditions. There were positive and significant effects of hydrochar-based inoculation on the root and shoot growth of soybean as compared to uninoculated plants grown under irrigated and drought conditions. The drought stress significantly inhibited the symbiotic performance of rhizobia with soybean. Soybean inoculated with hydrochar-based B. japonicum produced twofold more nodules under drought stress conditions as compared to plants inoculated with a commercial preparation/inoculant carrier B. japonicum (HISTICK). The N concentration of inoculated plants with hydrochar-based B. japonicum was by 31% higher than that of un-inoculated plants grown in pots and by 22% for HISTICK. Furthermore, the soybean treated with hydrochar-based B. japonicum showed higher grain yield of 29% under irrigated conditions and 40% higher under rainfed condition compared to un-inoculated plants. In conclusion, the obtained results proved the potential of hydrochar-based B. japonicum inoculant for soybean in terms of increased symbiotic performance and agronomic traits, especially under rainfed conditions.

The effects of biochar on plant growth vary depending on the applied biochar type, study site environmental conditions, microbial species, and plant–microbial interactions. The objectives of the present study were therefore to assess 1) the response of growth parameters of lupin and root disease incidence to the application of three biochar types in a loamy sandy soil, and 2) the role of endophytic bacteria in biological control of root rot disease incidence in lupin after the amendment of soil with different biochar types. As biochar types we tested (i) hydrochar (HTC) from maize silage, (ii) pyrolysis char from maize (MBC), and (iii) pyrolysis char from wood (WBC) at three different concentrations (1%, 2%, and 3% of char as soil amendments). There were no significant effects in lupin shoot and root growth in soils amended with WBC at any of the concentrations. MBC did not affect plant growth except for root dry weight at 2% MBC. HTC char at 2% concentration, significantly increased the root dry weight of lupin by 54–75%, and shoot dry weight by 21–25%. Lupin plants grown in soil amended with 2% and 3% WBC and MBC chars showed 40–50% and 10–20% disease symptoms, respectively. Plants grown in soil without biochar and with HTC char were healthy, and no disease incidence occurred. Pseudomonas putida L2 and Stenotrophomonas pavanii L8 isolates demonstrated a disease reduction compared to un-inoculated plants under MBC and WBC amended soil that was infested with Fusarium solani.

Radioactive cesium (137Cs) in distinct soil fractions provides key information to its bioavailability, and therefore determining the effect of soil characteristics and land use types on existing fractions of 137Cs in soils is important for predicting future 137Cs mobility in Fukushima. Thus, the objective of this study was to investigate the influence of soil characteristics and land use types on sequentially extracted fractions of 137Cs in Fukushima. In this study, five coniferous forest soils, eight arable soils, and eight paddy rice soils were sampled in 2012 and 2013. The 137Cs in the soils were separated into four fractions; water-soluble, exchangeable, organic matter-bound and residual fractions. More than 90% of the soil 137Cs fraction for arable and paddy rice soils was found in the residual fraction, implying significantly reduced bioavailable 137Cs with higher fixation. In contrast, forest soils measured higher exchangeable and organic matter-bound fractions of 5%−33% and 9%−44%, respectively, implying future 137Cs mobility in the forest ecosystem. Correlation analysis showed a significant negative correlation (p < 0.05) between the organic matter fraction and residual fraction in both arable and paddy rice soils. There was a significant positive correlation (p < 0.05) for both exchangeable and residual fractions with cation exchange capacity (CEC), total carbon (TC) and total nitrogen (TN) values in arable soils. Organic matter content influenced both exchangeable and residual fractions. It was not clear whether organic matter played a direct role in 137Cs fixation or mobility in the agricultural soils. In paddy rice soils, the organic matter fraction showed a significant negative correlation with TC and TN values. Soil pH was significantly negatively correlated (p < 0.05) with both water-soluble and residual fractions in forest soils but positively (p < 0.1) with the organically bound 137Cs fraction.

Conservation tillage techniques offer considerably reduced soil erosion and improved soil structure but they are rarely used in organic farming systems due to the potentially increased weed pressure. For the use in the transition period to conservation tillage in organic farming, this study investigated the dry matter production, weed suppression and grain yield of winter and spring faba bean (Vicia faba L.), field pea (Pisum sativum L.) and spring narrow-leafed lupin (Lupinus angustifolius L.), monocropped and intercropped with winter wheat (Triticum aestivum L.; winter crops) and oats (Avena sativa L.; spring crops). The different species were grown in no-tillage, reduced tillage and plough tillage systems at three sites in south-eastern Germany. In the no-tillage system the winter field pea grain yields of up to 3.39 Mg ha–1 were similar to the plough tillage system. For spring faba bean and field pea the yield in the reduced tillage system amounted to 2.92 and 3.29 Mg ha–1, respectively which was similar to the plough tillage system, but exceeded not 2.15 Mg ha–1 in the no-tillage system. Narrow-leafed lupin displayed consistently yields below 0.65 Mg ha–1 in the no-tillage system. Normal leafed winter field pea appeared best suited for the transition period to an organic no-tillage system due to the autumn seeding and its high competitive ability. Spring faba bean and field pea can be grown successfully in the reduced tillage system. Intercropping can increase the total grain yield and weed competition as long as sufficient soil nitrogen resources are plant available.

Nitrogen (N) in soybean (Glycine max L.) plants derived from biological nitrogen fixation was shown to be a sustainable N resource to substitute for N fertilizer. However, the limited water supply in sandy soil is a critical factor for soybean nodulation and crop growth. This study investigated the potential mechanism of the effect of biochar and irrigation on the soybean-Rhizobium symbiotic performance and soil biological activity in a field trial. In the absence of N fertilizer, 10 t ha−1 of black cherry wood-derived biochar were applied under irrigated and rainfed conditions on an experimental, sandy field site. The plant biomass, plant nutrient concentrations, nodule number, nodule leghemoglobin content, soil enzyme activities, and soil-available nutrients were examined. Our results show that biochar application caused a significant increase in the nodule number by 35% in the irrigated condition. Shoot biomass and soil fluorescein diacetate hydrolytic activity were significantly increased by irrigation in comparison to the rainfed condition. The activity of soil protease reduced significantly, by 8%, with the biochar application in the irrigated condition. Further, a linear correlation analysis and redundancy analysis performed on the plant, nodule, and soil variables suggested that the biochar application may affect soybean N uptake in the sandy field. Nodulation was enhanced with biochar addition, however, the plant N concentration and nodule Lb content remained unaffected.

Rainfed agriculture constitutes around 80% of the world’s agricultural land, achieving the lowest on-farm crop yields and greatest on-farm water losses. Much of this land is in developing countries, including sub-Saharan Africa (SSA), where hunger is chronic. The primary constraint of rainfed agriculture—frequently experienced in SSA—is water scarcity, heightened by the unpredictability of season onset, erratic rainfall, as well as the inability of farmers to provide adequate soil and crop management. Farmers react differently to constraints, making a variety of choices—including the timing of planting, type of land cultivation, fertilization, and scattered fields, among many others. Limited information is available on the combined effects of these strategies for improving crop yield and water use efficiency (WUE). An experiment was co-conducted with farmers over four consecutive rainy seasons (2014−2018) in Tanzania, to evaluate these strategies for single and joint effects in improving yield and WUE on rainfed pearl millet (Pennisetum glaucum (L.) R.Br.). The treatments used were flat cultivation both without and with microdosing, as well as tied ridging without and with microdose interaction, with different planting dates depending on farmers’ decisions. Results show that farmers react differently to the early, normal, or late onset of the rainy season, and cumulative rainfall during its onset, which affects their decisions regarding planting dates, yield, and WUE. Microdose fertilization increases both the yield and WUE of pearl millet significantly, with greater effects obtained using tied ridging compared to flat cultivation. For low-income smallholder farmers in a semi-arid agroclimate, using tied ridging with microdosing during early planting is an effective response to spatiotemporal rainfall variability and poor soils.

Establishing food security in sub-Saharan African countries requires a comprehensive and high resolution understanding of the driving factors of crop production. Poor soil and adverse climate conditions are among the major drivers of poor regional crop production. Drought and rainfall variability challenges are not fully being addressed by rainfed producers in semiarid areas. In this study, we analysed the spatiotemporal rainfall variability (STRV) and its effects on pearl millet yield using two seasons of data collected from 38 rain gauge stations scattered randomly in farm plots within a 1500 ha area of semiarid central Tanzania. The STRV effects on pearl millet yield under flat and tied ridge management were analysed. Our results show that seasonal rainfall can vary significantly for neighboring fields at distances of less than 200 m, which impacts yield. The STRV for daily rainfall was found to be more critical than for total seasonal rainfall amounts. Scattering fields can help farmers avoid total harvest loss by obtaining at least some yield from the areas that received adequate rain. The use of tied ridges is recommended to conserve soil moisture and improve yields more than flat cultivation in semiarid areas.

Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to measure the methane (CH4) fluxes in a flooded rice paddy field. Intensive monitoring using the CC method was conducted at 30, 60 and 90 days after transplanting (DAT) and after harvest (AHV). An EC tower was installed at the centre of the experimental site to provide continuous measurements during the rice cropping season. The CC method resulted in CH4 flux averages that were 58%, 81%, 94% and 57% higher than those measured by the EC method at 30, 60 and 90 DAT and after harvest (AHV), respectively. A footprint analysis showed that the area covered by the EC method in this study included non-homogeneous land use types. The different strengths and weaknesses of the CC and EC methods can complement each other, and the use of both methods together leads to a better understanding of CH4 emissions from paddy fields.

Spatiotemporal rainfall variability and low soil fertility are the primary crop production challenges facing poor farmers in semi-arid environments. However, there are few solutions for addressing these challenges. The literature provides several crop upgrading strategies (UPS) for improving crop yields, and biophysical models are used to simulate these strategies. However, the suitability of UPS is limited by systemization of their areas of application and the need to cope with the challenges faced by poor farmers. In this study, we reviewed 187 papers from peer-reviewed journals, conferences and reports that discuss UPS suitable for cereals and biophysical models used to assist in the selection of UPS in semi-arid areas. We found that four UPS were the most suitable, namely tied ridges, microdose fertilization, varying sowing dates, and field scattering. The DSSAT, APSIM and AquaCrop models adequately simulate these UPS. This work provides a systemization of crop UPS and models in semi-arid areas that can be applied by scientists and planners.

The decline in soil productivity amidst efforts to increase crop yield in Sub Saharan Africa (SSA) has made it imperative to assess the current fertilization management approaches. This study was conducted in two agroecological zones (i.e., Guinea Savannah (GS) and Deciduous forest (DF)) of Ghana to evaluate how different fertilization schemes in the long term (>5 years) impacted the soil biochemical properties. Soil samples under four fertilization schemes (inorganic fertilizer only, low-to-medium organic residues only, inorganic fertilizers plus low-to-medium organic residues, and no fertilization) from 20 farmers’ field were sampled from March to April 2015. Soil biochemical quality indicators were determined using standard procedures. Overall, the average chemical and microbial biomass contents for most indicators were significantly higher in DF compared to GS. Relative to the reference sites, soil quality improvement were observed under inorganic fertilization in both agroecologies in contrast to significant soil deterioration (26.5%) under sole organic residue application in GS. Furthermore, the results showed that increased inorganic fertilization rate alone or combination with organic residues improved soil quality relative to the reference. The present results suggest the need to raise the current fertilizer application rates, especially in GS in order to enhance optimum soil productivity.